In the field of photomechanical processing, there is a demand for photographic materials with a good ability to reproduce originals, for stable processing solutions and for simple processing solution replenishment methods, etc., in order to cope with the diversity and complexity of printed matter.
In processes for line image photography in particular, original documents may be prepared by pasting up photoset characters, handwritten characters, illustrations and dot images, etc. These original documents may contain mixtures of images with different densities or line widths. There is therefore a strong demand for platemaking cameras, photographic materials and image forming methods that will permit good reproduction of such original documents.
Further, magnification (spread) and reduction (choke) of halftone photographs is a common practice in platemaking for catalogs and large posters. But in platemaking using enlargement of dots, the result is a coarsening of line counts and a photographing of blurred points. With reduction of dots, the result is photographing of an image in which the line/inch count is greater and the dots are finer than in the original. Therefore, there is a need for an image forming method that affords still greater latitude in order to ensure reproduction of halftone gradations.
Halogen lamps and xenon lamps are used as light sources for platemaking cameras. Normally the photographic material is orthosensitized in order to give the requisite photographic speed for these light sources. However, it has been found that orthosensitized photographic material is strongly affected by the chromatic aberration of lenses, and consequently image quality is likely to deteriorate. This deterioration is more marked with xenon-lamp light sources.
A known system for meeting the demand for wider latitude is one in which image portions and non-image portions are clearly distinguished. Further, line or dot images with a high contrast and a high blackening density are produced by a hydroquinone developer in which the effective concentration of sulfite ions is very low (usually 0.1 mol/l or less) to process lithographic silver halide light-sensitive materials comprising silver chlorobromides (with a silver chloride content of at least 50%). However, with this method, since the sulfite ion concentration is low, development is very unstable against air oxidation. Consequently, that method was used with a variety of adjustments made to keep the solution activity stable and the processing speed was very slow. This lowered working efficiency.
There has therefore been a demand for image forming systems which eliminate the instability in image formation that exists with development methods such as those described above (a lithographic development system), which effect development with a processing solution possessing a good storage stability, and which achieve superhigh contrast photographic characteristics. One such system comprises the formation of superhigh contrast negative images with a gamma greater than 10 by using a developer that has a pH of 11.0-12.3, contains 0.15 mol/l or more of sulfurous acid preservative and has a good storage stability to process surface latent image silver halide photographic material which contains specific acylhydrazine compounds, as seen in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606 and 4,311,781. With earlier superhigh contrast image formation it was possible to use only silver chlorobromides with a high silver chloride content, and it is a feature of this new image forming system that it is also possible to use silver iodobromide and silver chloroiodobromide.
The above imaging system has an outstanding halftone quality, rapid and stable processing and good reproducibility of originals. But there is a demand for a system where the reproducibility of the original is further improved in order to cope with the recent diversity in printed matter.
JP-A-61-213847 (The term "JP-A" as used herein means an "unexamined published Japanese patent application") and U.S. Pat. No. 4,684,604 disclose light-sensitive materials containing redox compounds which release development inhibitors as a result of oxidation and describe an attempt to extend the range of gradation reproduction. However, if these redox compounds are added to light-sensitive materials in amounts sufficient to improve reproducibility of line images and dot images in a superhigh contrast processing system using hydrazine derivatives, an outflow of part of the development inhibitors released occurs at the time of development processing. Continued processing of large quantities of light-sensitive material containing these redox compounds results in gradual accumulation of development inhibitors in the developer, and when the exhausted developer that has been employed in processing is used in development processing, the result is hindrance of the achievement of high contrast and a fall in the photographic speed. In particular, if other light-sensitive photography materials contact light-sensitive materials, scanner light-sensitive materials or photographic light-sensitive materials, etc., are developed as well as the light-sensitive materials containing these redox compounds in a single automatic development unit, there is the problem of photographically adverse effects on these other light-sensitive materials.
Since there are restrictions on the amount of such redox compounds used, it is impossible to achieve thoroughly satisfactory effects and light-sensitive materials, and development processing solutions can be used only in a closed system that is restricted to a narrow range.